题目

Time and how we experience it have always puzzled us. Physicists have created fascinating theories, but their time is measured by a pendulum (钟摆) and is not psychological time, which leaps with little regard to the clock or calendar. As someone who understood the distinction observed, “When you sit with a nice girl for two hours it seems like a minute, but when you sit on a hot stove, a minute seems like two hours.” Psychologists have long noticed that larger units of time, such as months and years, fly on swifter wings as we age. They also note that the more time is structured 如图所示，OA为一根重50N的匀质杆，O端与墙用铰链相接，A端挂着重80N的重物，用细绳拉住杆的P点，AP为杆长的，细绳呈水平方向，杆与竖直墙成60°角．细绳中的张力T=_______N．